1. Technical Field
The present invention relates to a wireless power transmission apparatus and a transmission method thereof.
2. Description of the Related Art
With the development of a wireless communication technology, Ubiquitous info-tech environment has been being built so that everybody can transmit and receive his/her desired information at anytime regardless of locations. However, most of the information communication devices has been still operated by a battery and is supplied with power through a wired power cord, such that the use of the information communication devices has been limited. Therefore, wireless information network environment cannot completely be free until a problem of a power supply for a terminal is solved.
In order to solve the problem, many technologies to wirelessly transmit power have been developed.
An example of a representative technology may include a microwave receive type technology using microwave, a magnetic induction type technology using magnetic field, and a magnetic resonance technology using energy conversion between magnetic field and electric field, or the like.
In this case, the microwave receive type technology radiates microwave to the air through an antenna, such that power can be transmitted up to a long distance. However, the microwave receive type technology greatly increases radiation loss in the air, such that there is a limitation in efficiency of power transmission. In addition, the magnetic induction type technology, which is a technology using the coupling of magnetic energy due to a primary coil of a transmitting side and a secondary coil of a receiving side, has the high efficiency of power transmission. However, the magnetic induction technology closes the primary coil of the transmitting side and the secondary coil of the receiving side at a short distance on the order of several mm for power transmission. In addition, there are problems in that the efficiency of power transmission is rapidly changed according to the coil alignment of the primary coil of the transmitting side and the secondary coil of the receiving side and the caloric value is increased.
Therefore, the magnetic resonance technology is similar to the magnetic induction type technology but transmits power in the magnetic energy type by concentrating energy in a specific resonance frequency due to a coil type inductor L and a capacitor C.
The magnetic resonance technology can transmit relatively larger power up to several meters but requires a high quality factor.
That is, the magnetic resonance technology has a disadvantage in that the efficiency thereof is rapidly changed according to whether impedance is matched and whether the resonance frequencies between the LC coil of the transmitting side and the LC coil of the receiving side coincide with each other.
In particular, the impedance mismatch according to the change in distance between the transmitting side and the receiving side is a main factor preventing the maximum wireless power transmission in the wireless power transmission.
The magnetic induction technology according to the prior art mounts communication devices (for example, transceiver) in the transmitting side and the receiving side to control the above-mentioned problems through the communication between the transmitting side and the receiving side.
However, when the communication devices (for example, transceiver) is separately mounted, there are problems in that the costs of the wireless power transmission apparatus and reception apparatus are increased and the configuration of the apparatus is complicated.